Answer:
Pi(3.14) radians or 180º degrees
Explanation:
First of all, we need to obtain the wavelength of a wave traveling to the speed of sound and 420 Hz of frequency.
The formula is:

where l = wavelength in meters
With current values:
l = 336 [m/s]/420[1/s] = 0.8 meters
Since a complete cycle (360º or 2pi radians) needs 0.8 meters to complete, 0.4 meters or 40 cm is just half of it, making a 180º degree phase or 3.14 radians.
Answer: 
Explanation:
Given
Mass of particle is 
Charge of particle is 
Electrostatic force must balance the weight of the particle

Direction of the electric field is in upward direction such that it opposes the gravity force.
Answer:

Explanation:
As we know that there is no external torque on the system of platform, banana and the monkey
so the angular momentum of the system will remains conserved
so here we can say


here we know that





Now from above equation



Answer:
es un motor de combustión interna con encendido por chispa.